Highlight most recent messages in a youtube stream chat

chat.js

// ==UserScript==
// @name         Chat Announcer Thingy
// @namespace    https://manuelgu.eu
// @version      1.0
// @description  Try to take over the world!
// @author       manuelgu
// @match        https://www.youtube.com/live_chat*
// @grant        none
// ==/UserScript==

// Do the magic
addGlobalStyle('.comment-text { -webkit-animation: seconds 1.0s forwards; -webkit-animation-iteration-count: 1; -webkit-animation-delay: 3s; animation: seconds 1.0s forwards; animation-iteration-count: 3; animation-delay: 1s; position: relative; background: #39FF14; padding: 30px 30px 30px 3px; } @-webkit-keyframes seconds { 0% { opacity: 1; } 20% { background-color: #F08080; } 40% { background-color: #39FF14; } 60% { background-color: #F08080; } 80% { background-color: #39FF14; } 100% { opacity: 1; background: white; } } @keyframes seconds { 0% { opacity: 1; } 20% { background-color: #F08080; } 40% { background-color: #39FF14; } 60% { background-color: #F08080; } 80% { background-color: #39FF14; } 100% { opacity: 1; background: white; } }');

// Edit Global CSS
function addGlobalStyle(css) {
    var head, style;
    head = document.getElementsByTagName('head')[0];
    if (!head) { return; }
    style = document.createElement('style');
    style.type = 'text/css';
    style.innerHTML = css;
    head.appendChild(style);
}